1. Field of the Invention
The present invention relates to apparatus for inspecting and reconditioning used pipe and tool joints. More particularly, the present invention is directed to a tool joint reworking device for milling exterior surfaces and refacing both shoulders of a two-shoulder tool joint.
An example of a tool joint that needs frequent inspection and reconditioning is a tool joint used for connecting drill pipe together. The present invention is described in connection with such tool joints, bearing in mind it has equal application to pipes and other types of pipe joints.
The term tool joint is a well-known descriptive name for the couplings at either end of a drill pipe. Drill pipes are removed and added numerous times during the drilling operation and subjected to fluids containing abrasive materials, to significantly wear the screw threads and tool joint faces. Used tool joints must be inspected frequently to prevent leakage at the tool joints and to eliminate uneven tool joint faces that can make it difficult to disengage the tool joints.
2. Description of the Related Art
In the past it has been the practice to individually inspect each tool joint at the rig site with a gauging tool to detect the thread wear and irregularities in the tool joint face that cannot be located by visual inspection. The used drill pipe that had to be refaced was shipped to a machine shop where a lathe type apparatus was set up to rework the tool joint face and, usually at the same time, to rethread the tool joint. Considerable time was involved in getting the used pipe to the shop and, in many cases, rethreading of a drill pipe was not necessary even though the tool joint face had to be reworked. The machine in the shop that performed the refacing and rethreading operation was large and expensive, discouraging portable operation at the rig site.
In the refacing of a tool joint it is important that the new tool joint face be cut in relation to the axis of the tool joint, as determined by the screw thread. Errors up to 35/1000 of an inch have been measured on make-up shoulders refaced by a stationary machine in a shop. When a tool joint has part of its make-up shoulder 35/1000 of an inch lower than the rest of the shoulder, the tool joint will leak badly during drilling operations. The accurate alignment of the cutting tool is accomplished in the shop machinery by aligned chucks and, usually, the threads of the tool joint are reworked, to assure proper relationship with the tool joint face. The need remains for a refacing device that is portable and inexpensive enough for a tool pusher to have a set up at the rig site to inspect a tool joint and perform the refacing operation.
Often during drilling operations a pipe will be bent. When an operator attempts to reface the make-up shoulder of a tool joint on a bent pipe, using a stationary refacing device in a machine shop, the result is usually that the make-up shoulder is not refaced evenly, resulting in a tool joint that during operation will leak badly. The need remains for a refacing device that is portable and inexpensive enough for a tool pusher to have a set up at the rig site to not only inspect and reface tool joints on straight pipe, but also to inspect and reface tool joints on bent pipe.
A prior invention by the inventor of the present invention provided an apparatus for the refacing of tool joints having only make-up shoulders. That invention is disclosed in U.S. Pat. No. 3,181,398 issued May 4, 1965 to J. N. Rogers, which is incorporated herein by reference. Although the prior apparatus was excellent for refacing tool joints having only make-up shoulders, it is inadequate for refacing tool joints having make-up and secondary shoulders. Since the industry is using an increasing number of tool joints having both make-up shoulders and secondary shoulders in drilling operations, the need exists for a refacing device that can reface both the make-up shoulder and the secondary shoulder of a tool joint, while maintaining the original distance between those two shoulders.